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https://issues.apache.org/jira/browse/AMQ-6027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14997328#comment-14997328
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Timothy Bish commented on AMQ-6027:
-----------------------------------

Nice, that's a big chunk of work!  Looking forward to see those docs :)

> Dynamic network demand should support Virtual Destination consumers
> -------------------------------------------------------------------
>
>                 Key: AMQ-6027
>                 URL: https://issues.apache.org/jira/browse/AMQ-6027
>             Project: ActiveMQ
>          Issue Type: New Feature
>          Components: Broker
>    Affects Versions: 5.12.1
>            Reporter: Christopher L. Shannon
>            Assignee: Christopher L. Shannon
>             Fix For: 5.13.0
>
>
> Currently the broker supports the notion of 
> {{dynamicallyIncludedDestinations}}, where messages will only be sent across 
> a network of brokers if there is a consumer that exists on that destination.  
> This is good because it reduces the amount of traffic if there are no 
> consumers, however it doesn't take into account any virtual/composite 
> destinations that might exist or the consumers on those virtual/composite 
> destinations.  I'd like to be able to create demand and have messages flow 
> based on Virtual Destination creation, either on start up or dynamically by 
> the runtime configuration plugins, or by new consumers on a Virtual 
> Destination.
> So for example, if there are two brokers networked and on Broker A messages 
> are published to a topic, normally those messages only get passed to Broker B 
> if there is a consumer on that topic when setting 
> dynamicallyIncludedDestinations to true.  I want to have an option so that a 
> virtual destination setup on Broker B that forwards that topic to a queue 
> will trigger messages to start flowing from Broker A to Broker B.  
> Messages could start flowing either simply based on the existence of the 
> Virtual Destination (likely used for the case of a topic forwarding to a 
> queue, so messages accumulate on the queue) or based on there being a 
> consumer on the forwarded destination (likely used for the case of a queue 
> forwarding to a topic). 
> I've done some prototyping work here already and my plan is to keep track of 
> Virtual Destination consumers (configurable by the existence of the virtual 
> destination or by the fact that a real consumer exists on it) and to create a 
> new advisory topic where the broker can publish consumer advisories to.  The 
> prefix could be called something like:
> ActiveMQ.Advisory.VirtualDestination.Consumer.Topic
> ActiveMQ.Advisory.VirtualDestination.Consumer.Queue
> Advisory messages can be sent either when virtual destinations are 
> created/destroyed (kind of a dummy consumer) or when a real consumer comes 
> online for a virtual destination.  Then a remote broker could optionally 
> listen for those advisory messages and create or destroy a 
> DemandSubscription, just like is currently done for normal consumers.
> The default behavior out of the box would be to keep this behavior turned 
> off, but it could optionally be turned on through configuration.



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